Help with fonts and FOP

Do I have to do anything with a particular font to get it to work in FOP?
I've tried to generate PDFs using some different truetype fonts (verdana),
as well as some postscript fonts. Whenever I try anything other then the
generic font families (sans-serif) I get the following error when running
verdana:
WARNING: unknown font verdana so defaulted font to any.
Casing doesn't appear to be the problem because I tried verdana and Verdana
and still received the same error.
Thanks
-Scott
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